The present invention relates to a branching connection box for electrical circuits such as a junction box provided in mid course in a wiring harness of an automobile. More specifically the invention concerns a connection box in which the internal electrical components housed therein are separated and divided into a plurality of blocks and housed in various block cases, and the separate blocks are electrically connected directly with each other via bus-bars.
In the past, in order to facilitate the work of assembling a device having a plurality of electrically branching circuit parts in a branching connection box (such as a junction box), the device has been separated into a plurality of electrical components constituted by blocks. Separate bus-bars have been initially attached to block cases, and the individual blocks have been assembled into a branching connection box.
For example, in the junction box 1 shown in FIG. 11 of the accompanying drawings there are three separate blocks A, B and C which are incorporated into a housing 2 of a junction box 1.
The separate blocks A, B and C are connected electrically by a method employing sub-leads, or by a method using screws to fasten together the bus-bars protruding from the separate blocks.
The above-mentioned method employing sub-leads involves the provision of couplers A-1, B-1 and C-1 in the blocks A, B and C. As shown in FIG. 12, sub-lead 3 is provided having connectors a, b and c attached to the tips of branching wires W1, W2 and W3. The connectors a, b and c are connected in use to respective couplers A-1, B-1, C-1 on the outsides of the blocks, and a wire W4 linked to the branching wires W1, W2 and W3 of the said sub-lead 3 is typically connected to an external power source.
FIG. 13 shows by way of example, the method of using screws to fasten together the bus-bars. The bus-bar 4a of the block A extends to the blocks B and C respectively; the bus-bars 4b of the block B and the bus-bar 4a are fastened by screwing at point P1, the bus-bar 4c of the block C and the bus-bar 4a are fastened by screwing at point P2, and the bus-bar 4a is connected to an external power source.
The existing method employing sub-leads has problems in that it increases the dimensions of the branching connection box because it requires the provision of couplers in the block cases of each block and it requires a space for housing the branching wires and sub-lead connectors.
Furthermore, the latter method using screws to fasten together the bus-bars has problems in that it requires laborious assembly work because there are two screw fastening locations P1 and P2 when the separation is into three blocks as shown in FIG. 13, the screw fastening locations increase commensurately as the number of separate blocks increases, and in that it again increases the dimensions of the branching connection box due to the space taken up by the screw-fastening portions.
The present invention aims to resolve the above-mentioned problems by providing an application and method wherein the bus-bars of separate blocks are directly connected with each other, and specifically to provide a single fastening location even in junction boxes having three or more units to be connected. The invention also facilitates assembly of such boxes, reduces the dimensions thereof and can achieve common use of busbars and block cases of separate blocks.
In order to achieve the above-mentioned aims, the present invention provides an electrical assembly comprising a housing, a plurality of electrical components constituted by blocks and arranged within the housing, each electrical component having an electrical connection protruding therefrom, the respective electrical connections coinciding substantially at the centre of said housing in a stack and being fastened together directly to electrically connect said components.
Preferably, the terminals include a respective aperture, the aperture being aligned in the stack and connected by a fastener, preferably a screw and nut fastener, passing therethrough.
Each block is placed in the housing, the block cases and bus-bars thereof being formed in such a way that the electrical terminals of the bus-bars projecting from the above-mentioned blocks are positioned in the centre of the housing.
In a preferred embodiment bus-bar projection openings from which the electrical terminals of the bus-bars project are provided in portions of the block cases of the separate blocks corresponding to the approximate centre of the housing, the electrical terminals of the bus-bars of the blocks projecting from the said bus-bar projection openings being stacked at the approximate centre of the housing and positioned so as to stack on the top surface of a nut fixed on one of the above-mentioned blocks. The terminals are fastened by passing a screw through screw holes formed in advance in the terminals of the bus-bars, the screw engaging the nut.
A configuration is preferably adopted in which the block cases of the above-mentioned separate blocks have identical shapes, bus-bar projection openings are provided in four corners of the said block cases, the electrical terminals of the bus-bars project from the said bus-bar projection openings, and, even when the orientations of the blocks in the housing are different, the electrical terminals of the bus-bars can be adapted to stack in one location in the approximate centre of the housing.
When three separate blocks are incorporated in the above-mentioned housing, a first block is preferably housed in one half of the housing and two identically shaped second and third blocks are housed in the other side; the electrical terminal of a bus-bar projects from a portion of the above-mentioned first block positioned in the centre of the housing, while, in both the second block and the third block, the electrical terminals of the bus-bars project into the centre of the housing in orientations altered by 180 degrees.
A configuration in which the above-mentioned block cases are given identical shapes allows common use of block cases and bus-bars, assuming identical electrical wiring circuits in the said blocks, using identical bus-bars (used after cutting unnecessary parts if necessary), the electrical terminals of the bus-bars projecting from the blocks symmetrically.
Preferably, the blocks are rectangular, the terminals projecting from each corner of each block.
It is preferable that longitudinal bus-bars are adopted as the bus-bars are attached to the above-mentioned blocks, and that the screw fastening takes place in one direction with respect to the electrical terminals of the bus-bars in a perpendicular direction.
In the housing of the present invention, the bus-bars are first attached to the block cases of the separate blocks and the electrical terminals of the said bus-bars are adapted to project from the respective block cases. These blocks are incorporated in predetermined positions inside the housing. At this time, a block to which a nut may have been previously attached is incorporated in such a way that the nut is positioned to be at the outside edge of the stack of electrical terminals.
Once all the blocks have been incorporated and the electrical terminals are stacked in the centre of the housing, a screw is inserted through the holes in the electrical terminals and screwed onto the nut to effect a fastening link.
Of the bus-bars directly connected in the way described above, one of the bus-bars is connected to an external power source by another screw fastening.
Because the electrical terminals of the bus-bars projecting from the separate blocks as described above have an arrangement whereby they are stacked in one location in the centre of the housing, there need only be one screw-fastening location and there need only be one screw-fastening operation as well. Furthermore, because there is only one screw-fastening location, the dimensions of the housing can be reduced.